Gatsby 4 Upgrade - SyntaxError: Invalid left-hand side in assignment

[anthonycolevinomofo]

Preliminary Checks

• This issue is not a duplicate. Before opening a new issue, please search existing issues: https://github.com/gatsbyjs/gatsby/issues
• This issue is not a question, feature request, RFC, or anything other than a bug report directly related to Gatsby. Please post those things in GitHub Discussions: https://github.com/gatsbyjs/gatsby/discussions

Description

When upgrading to gatsby 4 and node 20 I'm getting an issue with building that's appeared after successfully building for a few weeks.

• I've thoroughly checked through my codebase and even went as far to run a codemod for react 17 and nothing has stood out.
• Nothing environmental that I'm aware of has changed.
• I've tried updating various packages to no avail - I'm aware that I'm using gatsby version 5 for some plugins but downgrading them has had no effect.
• I've tried every possible solution I can think of several times over and removed pages, every plugin I'm using, and went as far as trying to upgrade to gatsby 5 and still faced the same issue.

Invalid left-hand side in assignment

 Error: /Users/xxx/.cache/page-ssr/routes/render-page.js:13771

"true" = namespaces;
 ^^^^^^

Reproduction Link

https://github.com/gatsbyjs/gatsby/files/14647093/package.json

Steps to Reproduce

Try to run a build with this package.json

Expected Result

Build to succeed

Actual Result

Build failing

Environment

System:
    OS: macOS 14.2.1
    CPU: (12) arm64 Apple M3 Pro
    Shell: 5.9 - /bin/zsh
  Binaries:
    Node: 20.11.0 - ~/.nvm/versions/node/v20.11.0/bin/node
    Yarn: 1.22.21 - ~/.nvm/versions/node/v20.11.0/bin/yarn
    npm: 10.4.0 - ~/.nvm/versions/node/v20.11.0/bin/npm
  Browsers:
    Chrome: 122.0.6261.129
    Safari: 17.2.1
  npmPackages:
    gatsby: ^4.25.8 => 4.25.8
    gatsby-background-image: ^1.6.0 => 1.6.0
    gatsby-plugin-advanced-sitemap: ^2.1.0 => 2.1.0
    gatsby-plugin-fresnel: ^1.0.1 => 1.1.0
    gatsby-plugin-hubspot: ^2.0.0 => 2.0.0
    gatsby-plugin-image: ^3.8.0 => 3.13.1
    gatsby-plugin-loadable-components-ssr: ^4.3.2 => 4.3.2
    gatsby-plugin-manifest: ^4.0.0 => 4.25.0
    gatsby-plugin-no-index: ^1.0.2 => 1.0.2
    gatsby-plugin-react-helmet: ^5.0.0 => 5.25.0
    gatsby-plugin-remove-console: ^0.0.2 => 0.0.2
    gatsby-plugin-robots-txt: ^1.8.0 => 1.8.0
    gatsby-plugin-segment-js: ^3.7.1 => 3.7.2
    gatsby-plugin-sharp: ^4.25.1 => 4.25.1
    gatsby-plugin-styled-components: ^5.25.0 => 5.25.0
    gatsby-plugin-typescript: ^4.0.0 => 4.25.0
    gatsby-source-filesystem: ^4.25.0 => 4.25.0
    gatsby-source-graphql: ^4.0.0 => 4.25.0
    gatsby-transformer-sharp: ^4.15.1 => 4.25.0

Config Flags

DEV_SSR: true